The Sea Ice Mechanics Initiative (SIMI)

Abstract

ABSTRACT The Sea Ice Mechanics Initiative (SIMI) is a five-year U. S. Navy Office of Naval Research (ONR) program. The main SIMI field experiment was in the Beaufort Sea from September 1993 through April 1994, with numerous other small field experiments, laboratory experiments, and modeling efforts. The goals of this program are to understand sea ice constitutive laws and fracture mechanics over the full range of geophysical scales, to determine the scaled responses to applied external forces, and to develop physically-based constitutive and fracture models. About twenty principal investigators are working to achieve these goals along with their associates. The SIMI experiments include ice stress, strain, strength, tilt, motion, temperature, and response to controlled load experiments. This work will provide new ice information for loads on structures and for Arctic operations, both private and government. INTRODUCTION The goals of the Sea Ice Mechanics Initiative (SIMI) Arctic research program are stated in the SIMI Summary Plan (Curtin,1993), These are:Understand sea ice constitutive laws and fracture mechanics over the full range of geophysical scales and determine the scaled responses to applied external forces.Develop physically-based constitutive and fracture models. These goals were developed at the Sea Ice Mechanics Workshop (Curtin, 1991), along with an assessment of the limits of current understanding, a list of priority research issues, and state-of-the-art methods for the many aspects of sea ice mechanics. Individual projects within the program were defined around the scale size used in the ice mechanics work. This paper describes SIMI, focusing on the field program initiated in September 1993. BACKGROUND The Office of Naval Research held a Sea Ice Mechanics Workshop at Airlie, Virginia on November 12-14, 1990, where sea ice mechanics was examined from different perspectives, both methodological (theoretical modeling, laboratory experiments, and field observations) and behavioral (material, structural, and acoustical aspects). The Workshop proceedings (Curtin, 1991) outline limits of current understanding, prioritizes research issues, and documents innovative methods of approach. The workshop participants included representatives from government agencies and laboratories as well as from universities, the oil industry, and other private sector engineers and scientists. The Workshop Proceedings were used to shape the five-year (1992-96) SIMI program. ONR sponsored another workshop at Dunsmuir Lodge, Sidney, British Columbia, Canada on October 12-14, 1992 (Curtin, 1993). During this workshop, the detailed plan for SIMI was worked out. The main field experiment included a drifting camp in the Beaufort Sea collecting data from Fall 1993 through Spring 1994. The SIMI plan and the field program are described below in a quote from Curtin (1991). "A major question in understanding and predicting the mechanical behavior of Arctic sea ice involves the effect of size on the dynamics. The notion that the scales of a specimen alone influences the operative physics has fundamental implications."